The decision to put its p-c unit on the block was expected, said Gretchen Roetzer, lead analyst for insurance brokerage with Fitch Ratings in Chicago.

"A lot of these brokers are looking at what core and non-core business they have and where they are looking to get the most bang for their buck with the existing business they have," she said, adding that the activity follows recent settlements by brokers to give up contingent commissions.

She noted that the p-c insurance business has not been a strong line of business for Aon and it is natural for the broker to investigate alternatives, as it did with its sale of Swett & Crawford.

"If they were going to look at divesting businesses, to focus on the core business, this would be something we would expect for them to look at alternatives for," she added.

James B. Auden, senior director, insurance, for Fitch, said if the firm does decide to sell it would be interesting to see what the money is used for. He suggested Aon could use the money for acquisitions but doubted there were many firms left, "that would make a difference to them. There could be some specialty business, but with their scale, there is not a lot out there that would boost their market share."

"A sale would be strategic," noted Ms. Roetzer, aimed at alignment of a business model, not a move to finance some other project.

Both Ms. Roetzer and Mr. Auden said that if Aon does decide to sell the businesses, it would not sell unless it received a fair price for the units. What that price would be they would not venture to guess at without more research.

The option of spinning off the units as a separate entity, as the company failed to do with Combined Insurance, its life insurance subsidiary, three years ago, does not appear to be on the table.

"It appears they are looking for a buyer and an appropriate price," said Ms. Roetzer. "It's not a fire sale."

Adam Klauber, managing director at Cochran, Caronia & Co., in Chicago, an investment banking firm to the insurance industry, said, the sale would help Aon move closer to being a pure broker.

He said the market for a sale is much better than it was when it tried to spin off Combined, but there are still not many buyers. The primary candidates to purchase would be either other carriers or private equity investors.

Mr. Klauber said proceeds from the deal, which Cochran, Caronia estimated could be worth between $1 billion and $1.5 billion, would probably be used to either pay down pension liabilities or buy back shares. Either move would strengthen the company, he added.